The present invention relates to a device for cleaning an inner pipe inserted into a gas- or oil-producing well. During gas or oil production, impurities are deposited onto the inner wall of the inner pipe that lines a gas or oil-producing well. In order to ensure efficient flow of the gas or oil the deposited impurities need to be removed on a consistent basis.
Thus far, impurities have been removed by the application of chemical agents to the inner to the inner wall of the inner pipe which results in the loosening of clinging grime. For many reasons, however, the use of the chemicals to remove the impurities is less than satisfactory. For example, such chemicals are a burden on the environment and can be harmful to users of the chemicals, e.g., the cleaning personnel. In addition, the use of chemicals to remove the impurities not only is time consuming but also requires the requires the cessation of flow of the gas or oil through the pipe which hampers production.
In view of the aforementioned disadvantages associated with chemical cleaning, attempts have been made to mechanically remove the impurities from the inner pipe using mechanical devices, e.g., whereby spray nozzles are introduced into the inner pipe. However, these spray nozzles did not have the necessary mechanical stability and reliability to accomplish the removal of the impurities from the inner pipe in an economical way.
In use, the mechanical devices are difficult to access and monitor and are subjected to high temperatures and atmospheres having high moisture content. Moreover, the mechanical devices are expected to function in dirt, sand, rocks, fluids and in work spaces that cramped while bearing extreme impact loads in the horizontal and transverse direction. Traditional mechanical devices have not been suitable for removing the impurities from the inner pipe for the following reasons: (1) the bearings of the mechanical devices are easily damaged due to overly small dimensioning and impact strain, as well as penetration of dirt; (2) the seals of the mechanical devices fail due to abrasion by foreign particles; (3) the rotors of the mechanical devices break due to excessive loading, lateral forces, and dynamic impact loading; (4) the components of the mechanical devices easily fragmented and broken; and (5) the brake system of the mechanical devices are exposed to excessive heat. In addition to the aforementioned drawbacks, the use mechanical devices can result in the fouling of the wall of the inner pipe and the clogging of the inner pipe, e.g., when so-called bridges form, in which particles of dirt are baked together in a layer which substantially closes off the cross section of the inner pipe. When bridges form, tools other than the mechanical devices, e.g., drills, must be used to unclog the inner pipe thereby adding costs to the impurity removal process.
Therefore, a need exists for a mechanical device having a compact design that functions efficiently in the aforementioned extreme conditions, e.g., a work space having small diameters and without the aforementioned problems associated with traditional mechanical devices.